The present invention relates as indicated to a fireplace heater, and relates more particularly to an airtight heater which can be placed in preexisting fireplace openings. The purpose of the invention is to use to the extent possible the heat developed in the firebox and return the same to the room for heating the same, as contrasted with normal fireplace constructions in which a substantial amount of the heat of combustion is passed upwardly into the chimney flue.
Various types of fireplace heaters are known in the prior art, with all of these operating on the basic principle of drawing room air into the heater in heat exchange with the combustion gases of the fireplace, and thereafter returning the heated room air to the room. A typical heat exchanger of this type is disclosed in U.S. Pat. No. 4,091,794 to James J. Stites, with the heat exchanger disclosed therein comprising a plurality of tubes which envelope the area of heat in the fireplace and through which air drawn from the room is forcibly passed and returned to the room following the heat exchange. Air is forced through the tubes from a header connected to a fan, and the heat exchange is solely through the heater tubes thereby resulting in substantial heat loss through the chimney flue. An exterior frame including doors is mounted over the sides and top of the hearth.
U.S. Pat. No. 4,096,849 to Moncrieff-Yeates discloses a fireplace heating unit which can be positioned in the fireplace opening, with room air passing by natural convection through channels outside of the firebox for heat exchange therewith prior to returning to the room. The unit is entirely open to the room at the front, and air is not forcibly directed through the channels around the firebox.
U.S. Pat. Nos. 4,117,827 and 4,004,731 also relate to heat exchange units which can be positioned in fireplace openings to place room air in indirect heat exchange with the products of combustion of the fireplace.